Re: Parsing funny arrows

Another way to figure it out is the shift/reduce conflict on @, which tells you it had two ways to recognize it. "Reduce" here means returning to your parser rule, so "shift" means btype wanted to recognize the @. Inspecting btype would then have shown that it was looking for a type application. On Sat, Aug 29, 2020, 03:17 Csongor Kiss wrote:

Thanks a lot Vlad and Shayne, that indeed did the trick!

Out of curiosity, how could I have figured out that this was the culprit? The parse error I got was a bit puzzling, and I couldn't find any flags that would give more information (I think I was looking for the parser equivalent of -ddump-tc-trace).

Best, Csongor

On 29 Aug 2020, at 00:51, Shayne Fletcher wrote:

On Fri, Aug 28, 2020 at 7:48 PM Shayne Fletcher < shayne.fletcher.50@gmail.com> wrote:

...

On Fri, Aug 28, 2020 at 7:38 PM Vladislav Zavialov wrote:

...

Hi Csongor,

I believe the reason for this failure is that a -> @m b gets parsed as a -> @(m b). Why is that? Because a ‘btype’ includes type-level application.

If you replace the ‘btype’ after PREFIX_AT with an ‘atype’, this particular issue should go away. At least that’s my hypothesis, I haven’t tested it.

I confirm that this is correct and with that change the example string reduces as hoped.

- Vlad

...

Also, with that correction there are no new shift/reduce conflicts. The original rule gave rise to 3.

-- Shayne Fletcher

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